Greenhouse

A greenhouse, glasshouse or greenhouse is a transparent construction that allows the secure and controlled cultivation of plants.

The replacement - traditionally made ​​of glass, now often also from transparent plastic sheets or films - both increases by the greenhouse effect, the temperature in the greenhouse, but on the other hand, it also protects the plants from rain or strong winds. By controlling various factors such as air temperature and the irrigation control the climate inside the greenhouse is possible. Therefore, the necessary conditions for growth of cultivated plants in them in greenhouses can be optimized or even created, such as a year-round vegetable production in Central European climate, only.

Greenhouses are primarily for horticultural production or cultivation, but also for research purposes or for ostentation (botanical gardens).

History

In the context of European colonialism, the fashion made ​​out to collect as perceived exotic ornamental and useful plants, especially from Asia, America and Australia. This so-called plant hunters allowed the miniature greenhouse developed in the 1830s by Nathaniel Ward now also the transport of sensitive plants to Europe. To obtain these tropical plants under European climatic conditions, an evolution of the orangeries was required. At the end of the 18th century, greenhouses emerged as a glass timber constructions, but only sporadically with the first glazed gable roofs, such as the " Iron House " in Stuttgart -Hohenheim (RF Hr. Fischer, 1789 or 1791). Another building type are the lean-to greenhouses, where a sloping glass roof of a shielding wall to the north massive " leaning ".

Impetus for the development of the greenhouse came from the pineapple cultivation in Europe. Especially in England the cultivation of this tropical fruit was popular in the 18th and 19th centuries. The time hardly transportable and therefore rare pineapple fruits were as status and prestige symbol of wealthy society groups consuming in small greenhouses ( pinery ) or covered with glass windows pits produced ( pineapple pit).

The industrialization opened up new possibilities of use of iron and glass as building materials. Beginning of the 19th century experimented in England George Stewart Mackenzie and John Loudon with the curvilinear houses, which are greenhouses with semicircular arched iron and glass roofs to maximize the use of sunlight evenly. Mackenzie designed in 1812 a quarter -sphere hothouse for peach and wine, which consisted of a glass quarter sphere in front of a brick wall. Louden built in 1818 at London Bayswather different experimental greenhouses to find the cheapest form of construction for optimal sunlight experimentally. He published 1817 Remarks on the Construction of Hothouses and 1818 Sketches Of Curvilinear Houses, which were received in Europe and influenced the further development of the glass house design significantly.

An early example of iron and glass greenhouse outside of the UK are the 1834-36 built by Charles Rohault de Fleury Serres in Paris in the Jardin des Plantes. In England built Joseph Paxton 1836-1841 The Great Conservatory ( Large house plants ) in the park of Chatsworth House, which model was built from 1841 to 1849 for the Palm House at Kew Gardens. 1850 was also produced in Chatsworth by a tropical water lilies Paxton House with heated pool, the Victoria Regia greenhouse. A highlight of the iron and glass wooden structure was erected in 1851 exhibition building Crystal Palace Paxton.

The earliest known hot-water central heating system was built in 1716 by Marten Trifvald for a greenhouse in Newcastle. However, until about the 1830s was the steam heating in greenhouses more widespread, replacing older single ovens.

These glass houses, also called "plant Museums", which staged the collated exhibits in the character of domination of nature and exoticism, spread in the second half of the 19th century in the cities of Europe and North America, especially in the botanical gardens and urban parks as commercial places of amusement. For example, in 1882 the Schönbrunn Palm House was opened in Vienna. In Berlin, was from 1905 to 1907, the Grand Pavilion in the Botanical Gardens. An outstanding example of the greenhouse architecture of the 19th century are the Serre du Congo and Grote Wintertuin in the park of the Royal Castle of Laken in the north of Brussels.

The first greenhouse in the shape of a geodesic dome was completed in 1960 Climatron in the Botanical Garden of Missouri at St. Louis. A well-known example of this form of construction are the greenhouses of the Eden Project opened in 2001, which is currently the world's largest greenhouses. In the late 1980s an attempt was made to achieve a self-sufficient ecosystem in the greenhouse of the Biosphere 2 project.

Structure and components of a greenhouse

Greenhouses and glasshouses there in very different sizes of a few square meters to giant palm houses.

Basic components of a greenhouse are:

• The mostly resting on one ( at the same time against ground frost protected ) Structural foundation of the greenhouse made ​​of masonry, wood, or, as is usual in commercial horticulture, from one made ​​of steel and / or aluminum metal construction.
• The light transmissive covering of glass, plastic films (eg PVC or PE, partly also in multi-layer or coated design for better durability and light transmission) or plastic plates ( for example, made ​​of Plexiglas (PMMA ), polycarbonate, glass-fiber reinforced polyester ( GUP ) or PVC). Plastic plates are often due to better insulation in the form of Holm chamber plates ( double-skin sheets - also called short SDP - or triple-wall sheets - also called short S3P ) used.
• The culture surfaces for the plants to be grown. A distinction ( suspended structures ) between different Beetformen, tables or hanging. The Bodenbeet has connection to the natural soil, the Grundbeet however, the culture -bearing substrate layer is separated from the natural ground by a barrier layer of concrete or foil. When Trogbeet the growing medium is usually incorporated in concrete troughs, the substrate layer has thus also in this no connection to the natural soil. The culture on tables is applied to potted plants; the tables and table tops are either fixed or also (for better space utilization by eliminating areas of paths ) executed displaced. Although slacks devices in the form of pendants for single pots, troughs, among other things can be increased floor space by use of space above the beds or tables, disadvantageous in suspension cultures but the obstruction of light incidence on low-lying croplands and is tricky to culture care.
• Means for venting for the purpose of influencing the oxygen and carbon dioxide content of the greenhouse air and to control the temperature.

Many Gewächs-/Glashäuser are also equipped with:

• Systems for irrigation or to irrigation
• Heating
• Facilities for shading or darkening, eg by providing demand as compact zusammenraffbarer Schattiergewebe.
• Electrical or electronic control technology ( Greenhouse computer ) for climate control and irrigation automation
• So-called energy shields as an additional insulation against heat loss, such as from UV stabilized bubble wrap
• Insect nets
• Lighting Equipment for artificial lighting of cultures
• CO2 fertilization plants for carbon dioxide fertilization
• Combined heat and power plants (combined heat and power)

Operation

A distinction is made in the greenhouses depending on inside temperature

• Kaltenhäuser for temperatures below 12 ° C,
• Tempered homes for temperatures of 12 ° C-18 ° C,
• Warm houses ( greenhouses, Eng. Hothouse ) for temperatures above 18 ° C.

When the sun shines, it comes in a greenhouse in a rapid and greater increase in the internal temperature compared to air and ground temperature outside the greenhouse. The reason for this is a kind of heat accumulation: the energy of solar radiation is first heated the soil, the plants and parts of the greenhouse, but from them again emitted heat radiation (infrared ) is held back by the largely impermeable for this covering of the greenhouse.

This greenhouse effect (appointment of J. Fourier ) is also used in residential buildings (winter gardens ) and roof surfaces used (eg workshops ), but also in much at orangeries and castles. The heated from the heated interior air is cooled only slightly in closed glass surfaces from the outside due to the low air exchange. In contrast, almost all the infrared radiation from the glass and the building itself in the room is reflected back ( " selective transparency ").

However, the internal temperature may increase to phytotoxic 35 ° C and more, on a normal sunny day. Hence, one must greenhouses can also reveal what is usually done with a roof or floor wall ventilation, also known as "First and sidewall ventilation flaps ".

Newer designs

Newer types, so-called convertible greenhouses can have their roof area largely pushed together. So that the inner temperature can be controlled to be almost equal to the outdoor temperature. This leads to a significant improvement of quality of cold crops and during the summer months.

Plastic films are for the commercial vegetable now widely used, some of which cover large areas and entire valley floors. In El Ejido are so many covered with plastic sheeting greenhouses, as nowhere else in Europe.

Modern technology is often initially used in research greenhouses. In plant experimental facility PhyTec the Forschungszentrum Jülich for example glasses from the solar industry are used which have maximum transparency and mechanical stability.

A completely new development is the Seawater Greenhouse ( seawater greenhouse ), which was developed in the 1990s for arid regions and its water demand is covered by sea water which is desalinated in the greenhouse itself. It uses the same water for cooling and incidentally produces drinking water.

Closed greenhouses

In a different direction closed greenhouses, such as the project Watergy ( a composition of water; engl water and gy, . Abbreviation and formula unit for Gray ). The idea of a closed system is simple, and is already in the Ward'schen bottle ( also Ward'sche box ) used: If the system is closed, no steam can escape and so water can be saved; In addition, further advantages ( S.U. ).

By adding water, and respiration of the plant is water vapor. This is collected in a central, high cooling tower and cooling the relative humidity is increased, so that the steam is condensed and the ( distilled ) water can be collected. The water can be used for irrigation or drinking again, that is, the system can also be used for the treatment of gray water.

The water vapor is condensed by means of cold water through a heat exchanger. This heated water can be stored in order to use it later for heating the greenhouse again. In this regard, there are two options: Either you need it overnight or during cold seasons. The former is realized relatively easily via water tanks, the latter option can camp of depth up to 200 m are needed ( in the ground). So can be smoothed extreme temperatures, which for some cultures - is essential - and if one wishes to grow all year round. This type of " heating " also makes sense from an economic and ecological point of view, in contrast to conventional heaters that run on electricity.

The closed system also brings with it the advantage that less CO2 to escape, which is needed by plants for photosynthesis. With increased CO2 concentration, which can be up to 3 times as high as in open systems, a significantly higher return can be achieved. CO2 can be "imported" into the greenhouse, for example, via pipelines from CO2 - emitting industries, by burning natural gas or produced directly in the greenhouse, for example, via composting.

The closed system, it is also unlikely that diseases or pests from entering.

Economic Importance

The Europeans were to the 1970s accustomed to buy seasonal vegetables and to use the classic winter vegetables such as cabbage and potatoes for the winter. Through preservation and later by the bill of fare Freezers remained varied in winter and spring. Then, however, first built Dutch and later southern European companies fruits and vegetables in increasingly extensive glasshouse complexes and were able by the end of the 1980s, a year-round supply of essential fruits and vegetables provide. The price of the goods is obviously higher outside the season. By default use of beneficial stocking by harmful insects and mites can be kept mostly below the damage threshold for a ( nützlingsschonenden ) insecticide use. In addition, today have greenhouses with stud wall heights of 4 m an optimal climate, so that there is less contamination with fungi.

The success of greenhouse crops has resulted in the German-speaking world to develop such systems. In Austria, for example, is the center of the vegetable cultivation for peppers and tomatoes in southern Seewinkel.

Soilless production / soil invertebrate culture

The soilless production (French soil -free production ), also soilless culture substrate or culture or hydroponics or hydroponics called, is a method of cultivation without the use of soil or earth -like substrates. The cultures, the majority of vegetables are planted in this earth a free material such as rockwool or coir, under well-defined nutrient and water supply in a greenhouse or in a hall, which can also be heated. This type of production is economically effective, but requires, depending on the conditions, a high energy input.

One advantage of soilless production is the independence of weather, climate and soil. This makes this type of production, particularly for sensitive plants such as tomatoes popular. Indispensable even it is in fungi, since these very narrow limits cultivation have.

Prohibited is the ground- free production of organic products, as in organic farming soil-less plant substrates are not allowed. For ( bio) mushrooms, seedlings and potted herbs this type of production may be used.

In nutrient solution grown plants and its fruits taste is often said or the difference of quality and taste between organic and hors sol - cultivation is controversial. Especially on the part of producers ( advertising, etc. ) is asserted that the mode of production not affecting the taste. Note the origin of the product. In exporting countries must be harvested in consideration of the durability of earlier acts accordingly to the taste.

Indeed, it is possible that many substances that produces a plant (in small amounts ), have not yet been discovered. It follows that the appropriate starting materials or factors missing in the substrate or the cultivation and finally in the product (eg as taste).

Soilless must be mandatorily applied in vertical greenhouses. Pilot projects and plans are in use and are considered as a future alternative solution in urban areas.

Greenhouse heating

Greenhouses are also Heizkanonen directly heated, in which the exhaust gases are fed directly into the greenhouse space. Use of porous burners or other catalytic burners, the combustion temperature of a flame can be lowered to below 1200 ° C, whereby nitrogen oxides are formed in the less -corrosive flue gas.

In the vicinity of lignite power plant in Neurath near Cologne since summer 2011, a greenhouse Park uses a portion of the waste heat. At 11 hectares ( 110,000 sq.m. = ) are, for example, Tomatoes grown.

The heating is provided, then the base of the greenhouse has to be insulated in the ground, either the outside ( " perimeter insulation " ), or inside non-porous solid with root plates ( for example of polystyrene or polyurethane ) for insulating. Otherwise, the base is a big cold bridge.

In Wuppertal - Herbringhausen greenhouses are heated with wood pellet heating system, with a large water heater stores the heated water is then distributed through a pipe system to control the climate.

Small greenhouses

In the small greenhouse is not about mass production, but the love of plants and the possibility to extend the gardening year. A small greenhouse allows, depending on the climate control heating, ventilation, shading, different types of use:

• The extended or year-round cultivation of vegetables and herbs in your own garden
• Own seedling
• Overwintering potted plants, fruit trees in tubs
• Forcing ( chives, cut flowers )
• Wine in less suitable climate
• Harboring of cold-sensitive or heat- loving plants Collections: cacti, bonsai, ferns, palms, orchids.

For the hobby gardener there is a large selection of small greenhouses. They differ, for example, in terms of size, design, roofing material, technical equipment ( temperature control devices, irrigation equipment).

Depending on the type of use and the resulting demand for heat in the winter months, heating is necessary. In order to save heating costs and also for environmental reasons should be given to thermal insulation when buying a greenhouse to be heated by appropriate design and roof coverings. On the other hand, the summer months are often very hot - according to important adequate ventilation and shading options can be.

In a small garden but sometimes also satisfy even one or two retired window to build a low greenhouse ( cold frame ) whose climate can be controlled by opening the glass surfaces.